1. Field of the Invention
The present invention relates to a thin film transistor, a photo-mask for defining a thin film transistor, and a method of making a thin film transistor, and more particularly, to a photo-mask for improving a channel length limitation of a thin film transistor, a thin film transistor with a short channel length, and a method of making the same.
2. Description of the Prior Art
In the thin film transistor liquid crystal display panel (TFT-LCD panel), a thin film transistor serves as a switch component controlling each pixel electrode. When the size and the resolution of the LCD panel improve, the size of the pixel electrode accordingly increases. Therefore, the thin film transistor has to provide a larger turn-on current (Ion) to enhance the charging ability. As known by the person skilled in the art, the quantity of the turn-on current is proportional to the channel width/length (W/L) ratio of the thin film transistor. The conventional method for enlarging the turn-on current is to increase the channel width of the thin film transistor. However, increasing the channel width of the thin film transistor may lead to some disadvantage, such as a lower aperture and an increasing load of resistances and capacitors. On the other hand, decreasing the channel length of the thin film transistor may also enlarge the turn-on current. But this method is difficult due to the limitation of the conventional photo-mask and the photolithographic process.